A transdermal patch can include a drug source, a porator, and an energy storage device on-board the patch. Conductive contact terminals can extend from the energy storage device for connection to an external source of power. The porator operates free of any concurrent connection to any external source of power. A switch can be used to make the selective electrical connection between the porator and the energy storage device. The switch can be arranged to respond to a manual user action after the patch has been adhered to skin, including separation of the porator from a remainder of the patch. Optionally, a series of switches can make electrical connections between the porator and respective individual energy storage devices.In another aspect, a transdermal patch includes a mechanical bias that applies a displacement force to the porator to thereby better ensure good physical contact between the porator and the skin.
